Which one of the following is not true regarding electromeric effect?

Consider the following structures:
$I.$ $CH_3-CH_2-COOH$
$II.$ $CH_3-CH(Cl)-COOH$
$III.$ $Cl-CH_2-CH_2-COOH$
$IV.$ $CH_3-CH_2-CH_2-COOH$
The correct order of their acidity is

Explain the delocalization of electrons in $CH_3-CH_2^+$ and $CH_3-CH=CH_2$.

Match List-$I$ with List-$II$:
| List-$I$ (Mechanism steps) | List-$II$ (Effect) |
| :--- | :--- |
| $(A)$ Aniline resonance structure | $(I)$ $-E$ effect |
| $(B)$ Electrophilic addition of $H^+$ to alkene | $(II)$ $-R$ effect |
| $(C)$ Nucleophilic addition of $CN^-$ to alkene | $(III)$ $+E$ effect |
| $(D)$ Nitrobenzene resonance structure | $(IV)$ $+R$ effect |
Choose the correct answer from the options given below:

Write the correct order of acidic strength for the following:
$(I) \ CH_3 - NO_2$
$(II) \ NO_2 - CH_2 - NO_2$
$(III) \ CH_3 - CH_2 - NO_2$
$(IV) \ (NO_2)_3CH$

Which of the following compounds has the maximum enol content?